The present invention relates a surface polishing apparatus for surface-polishing a plate-like workpiece, e.g., a semiconductor wafer, a wafer having an insulating film or a metal interconnection and used for a semiconductor circuit, a magnetic disk, or a glass substrate to a high degree of smoothness.
Recently, the surface polishing apparatuses disclosed in, e.g., Japanese Patent Laid-Open Nos. 4-33336, 5-69310, and 5-309559 have been used to polish semiconductor wafers, magnetic disks, and the like.
FIG. 7 shows a conventional surface polishing apparatus similar to those disclosed in the above references. In this surface polishing apparatus, a pressure holding plate 33 presses a workpiece 32 against the work surface (facing upward) of a disk-like polishing tool 31 which is rotated/driven. In this state, the apparatus performs surface polishing while supplying a polishing solution 34 to the work surface.
In the above conventional surface polishing apparatus, however, as shown in FIG. 8, with an increase in polishing time, the polishing rate (polishing amount/time) decreases because the work surface clogs up, and the polishing amount varies for each workpiece. In addition, since a polishing solution is discarded after it is used once, the running cost of a polishing solution is high.